Priority is claimed to British Patent Application No. 9828424.3, filed Dec. 24, 1998.
This invention relates to a tooth for a vehicle wheel. In particular, the invention relates to an improved tooth design for a landfill compactor vehicle wheel.
Large steel-wheeled vehicles, generally referred to as landfill compactor vehicles, are conventionally used to compact waste materials disposed of in landfill sites. Such vehicles have large toothed wheels (typically having a diameter of the order of 4 ft to 5.5 ft) which provide both traction for the vehicle and a means for breaking up and compacting the waste material.
The design of conventional landfill compactor vehicle wheels, and in particular the wheel teeth (which in many cases are removable so that they may be replaced when worn out) varies widely. With conventional tooth designs there can be a tendency for the compactor vehicle wheels to xe2x80x9cflick and fluffxe2x80x9d the tipping face of the landfill site. In other words, rather than being compacted into the surface, some relatively light materials can break away from the service and be disbursed by the wind which is clearly undesirable. One way of combating this problem is to import a cover which is spread on the face of the site. The problem has, however, increased in recent years with the introduction of Landfill Tax in the UK which has reduced the amount of heavy materials being disposed of in landfill sites. This has brought about a corresponding increase in wind-blown litter and/or an increase in the amount of cover material needed to combat the problem.
It is an object of the present invention to obviate or mitigate the above problem. The present invention achieves this by the provision of an improved vehicle tooth design.
It is a further object of the invention to provide a new method of manufacturing a vehicle wheel tooth.
According to a first aspect of the present invention there is provided a vehicle wheel tooth comprising a base, a wall extending upwardly from the periphery of the base towards a crest, the crest having a peripheral profile defined by the upper edge of the wall, wherein the wall is shaped such that the crest face is generally xe2x80x9cMxe2x80x9d shaped.
Preferably the wall is shaped by three depressions each defining a generally xe2x80x9cVxe2x80x9d or xe2x80x9cUxe2x80x9d shaped indentation in the peripheral profile of the crest face. Each of said depressions defines a channel in the wall of the tooth which extends from the crest towards the base, the channels mutually diverging. The channels preferably become both shallower and narrower towards the base of the tooth.
The tooth may for instance be shaped such that in the absence of said depressions the crest would have a generally rectangular peripheral profile with two opposing side edges.
In preferred embodiments of the tooth the base is generally rectangular having opposing front and rear edges and two opposing side edges shorter than said front and rear edges, wherein said wall comprises four faces (which are preferably mutually inclined) extending upwardly from respective base edges towards said crest.
According to a second aspect of the present invention there is provided a method of manufacturing a vehicle wheel tooth, the method comprising:
i) casting a base for the tooth by pouring a molten metal or metal alloy of a first type into a mold which defines the desired configuration of a base for the tooth;
ii) removing the base from the first mold and placing the pre-cast base in a second mold which defines the desired configuration of a cap for the tooth;
iii) pouring a molten metal or metal alloy of a second type into said second mold to cast the cap directly on to the pre-cast base.
According to a third aspect of the present invention there is provided a vehicle wheel tooth comprising a pre-cast base cast from a metal or metal alloy of a first type, and a cap cast directly onto the pre-cast base from a metal or metal alloy of a second type, the base and cap being keyed together.